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Objective: The therapeutic landscape for localized prostate cancer (PC) is evolving. Stereotactic radiotherapy (SRT) has been reported to be at least not inferior to standard radiotherapy, but the effect of androgen deprivation therapy (ADT) in this setting is still unknown and its use is left to clinical judgment. There is therefore the need to clarify the role of ADT in association with SRT, which is the aim of the present study.

Methods: We present a study protocol for a randomized, multi-institutional, Phase III clinical trial, designed to study SRT in unfavorable intermediate and a subclass of high-risk localized PC. Patients (pts) will be randomized 1:1 to SRT + ADT or SRT alone. SRT will consists in 36.25 Gy in 5 fractions, ADT will be a single administration of Triptorelin 22.5 mg concurrent to SRT. Primary end point will be biochemical disease-free survival. Secondary end points will be disease-free survival, freedom from local recurrence, freedom from regional recurrence, freedom from distant metastasis and overall survival (OS); quality of life QoL and patient reported outcomes will be an exploratory end point and will be scored with EPIC-26, EORTC PR 25, IPSS, IIEF questionnaires in SRT + ADT and SRT alone arms. Moreover, clinician reported acute and late toxicity, assessed with CTCAE v. 5.0 scales will be safety end points.

Results: Sample size is estimated of 310 pts. For acute toxicity and quality of life results are awaited after 6 months since last patient in, whereas, for efficacy end points and late toxicity mature results will be available 3-5 years after last patient in.

Conclusion: Evidence is insufficient to guide decision making concerning ADT administration in the new scenario of prostate ultra-hypofractionation. Hence, the need to investigate the ADT role in SRT specific setting.

Advances in knowledge: The stereotactic prostate radiotherapy with or without ADT trial (SPA Trial) has been designed to establish a new standard of care for SRT in localized unfavorable intermediate and a subclass of localized high risk PC.

Objectives: Right ventricular (RV) dysfunction carries elevated risk in acute pulmonary embolism (PE). An increased ratio between the size of the right and left ventricles (RV/LV ratio) is a biomarker of RV dysfunction. This study evaluated the reproducibility of RV/LV ratio measurement on CT pulmonary angiography (CTPA).

Methods: 20 inpatient CTPA scans performed to assess for acute PE were retrospectively identified from a tertiary UK centre. Each scan was evaluated by 14 radiologists who provided a qualitative overall opinion on the presence of RV dysfunction and measured the RV/LV ratio. Using a threshold of 1.0, the RV/LV ratio measurements were classified as positive (≥1.0) or negative (<1.0) for RV dysfunction. Interobserver agreement was quantified using the Fleiss κ and intraclass correlation coefficient (ICC).

Results: Qualitative opinion of RV dysfunction showed weak agreement (κ = 0.42, 95% CI 0.37-0.46). The mean RV/LV ratio measurement for all cases was 1.28 ± 0.68 with significant variation between reporters (p < 0.001). Although agreement for RV/LV measurement was good (ICC = 0.83, 95% CI 0.73-0.91), categorisation of RV dysfunction according to RV/LV ratio measurements showed weak agreement (κ = 0.46, 95% CI 0.41-0.50).

Conclusion: Both qualitative opinion and quantitative manual RV/LV ratio measurement show poor agreement for identifying RV dysfunction on CTPA.

Advances in knowledge: Caution should be exerted if using manual RV/LV ratio measurements to inform clinical risk stratification and management decisions.

Objective: To clarify the peripheral dose changes, especially in the eye lens and thyroid gland regions, using an acrylic-lead shield in cone-beam computed tomography (CBCT).

Methods: The acrylic-lead shield consists of system walls and a system mat. The radiophotoluminescence glass dosemeter was set on the eye lens and thyroid gland regions on the RANDO phantom. The system mat was laid under the RANDO phantom ranging from the top of the head to the shoulders, and then, the system walls shielded the phantom's head. Additionally, the phantom was covered anteriorly with a band that had the same shielding ability as the system mat to cover the thyroid gland region. Protocols for CBCT imaging of the thoracic or pelvic region in clinical practice were used. The measurement was performed with and without the acrylic-lead shield.

Results: The dose to the eye lens region was reduced by 45% using the system wall. Conversely, the dose to the thyroid gland was unchanged. The use of the system mat reduced the dose to the thyroid gland region by 47%, and the dose to the eye lens was reduced by 22%. The dose to the eye lens region decreased to the background level using the system walls and mat.

Conclusion: The newly proposed device using an acrylic-lead shield reduced the peripheral dose in CBCT imaging.

Advances in knowledge: Attention is focused on managing peripheral dose in image-guided radiation therapy. The peripheral dose reduction using the acrylic-lead shield is a new proposal in radiotherapy that has never been studied.

Objective: We evaluated the radiobiological effect of the irradiation time with the interruption time of stereotactic radiosurgery (SRS) using CyberKnife^® (CK) systemfor brain metastases.

Methods: We used the DICOM data and irradiation log file of the 10 patients with brain metastases from non-small-cell lung cancer (NSCLC) who underwent brain SRS. We defined the treatment time as the sum of the dose-delivery time and the interruption time during irradiations, and we used a microdosimetric kinetic model (MKM) to evaluate the radiobiological effects of the treatment time. The biological parameters, i.e. α₀, β₀, and the DNA repair constant rate (a + c), were acquired from NCI-H460 cell for the MKM. We calculated the radiobiological dose for the gross tumor volume (GTV_bio) to evaluate the treatment time's effect compared with no treatment time as a reference. The D95 (%) and the Radiation Therapy Oncology Group conformity index (RCI) and Paddick conformity index (PCI) were calculated as dosimetric indices. We used several DNA repair constant rates (a + c) (0.46, 1.0, and 2.0) to assess the radiobiological effect by varying the DNA repair date (a + c) values.

Results: The mean values of D95 (%), RCI, and PCI for GTV_bio were 98.8%, 0.90, and 0.80, respectively, and decreased with increasing treatment time. The mean values of D95 (%), RCI, and PCI of GTV_bio at 2.0 (a+c) value were 94.9%, 0.71, and 0.49, respectively.

Conclusion: The radiobiological effect of the treatment time on tumors was accurately evaluated with brain SRS using CK.

Advances in knowledge: There has been no published investigation of the radiobiological impact of the longer treatment time with multiple interruptions of SRS using a CK on the target dose distribution in a comparison with the use of a linac. Radiobiological dose assessment that takes into account treatment time in the physical dose in this study may allow more accurate dose assessment in SRS for metastatic brain tumors using CK.

Whole-body magnetic resonance imaging (WBMRI) is an increasingly popular technique in paediatric imaging. It provides high-resolution anatomical information, with the potential for further exciting developments in acquisition of functional data with advanced MR sequences and hybrid imaging with radionuclide tracers. WBMRI demonstrates the extent of disease in a range of multisystem conditions and, in some cases, disease burden prior to the onset of clinical features. The current applications of WBMRI in children are hereby reviewed, along with suggested anatomical stations and sequence protocols for acquisition.

Objectives: Whilst radiology is central to the modern practice of medicine, graduating doctors often feel unprepared for radiology in practice. Traditional radiological education focuses on image interpretation. Key areas which are undertaught include communication skills relating to the radiology department. We sought to design teaching to fill this important gap.

Methods: We developed a small group session using in situ simulation to enable final and penultimate year medical students to develop radiology-related communication and reasoning skills. Students were given realistic cases, and then challenged to gather further information and decide on appropriate radiology before having the opportunity to call a consultant radiologist on a hospital phone and simulate requesting the appropriate imaging with high fidelity. We evaluated the impact of the teaching through before-and-after Likert scales asking students about their confidence with various aspects of requesting imaging, and qualitatively through open-ended short answer questionnaires.

Results: The session was delivered to 99 students over 24 sessions. Self-reported confidence in discussing imaging increased from an average of 1.7/5 to 3.4/5 as a result of the teaching (p < 0.001) and students perceived that they had developed key skills in identifying and communicating relevant information.

Conclusions: The success of this innovative session suggests that it could form a key part of future undergraduate radiology education, and that the method could be applied in other areas to broaden the application of simulation.

Advances in knowledge: This study highlights a gap in undergraduate medical education. It describes and demonstrates the effectiveness of an intervention to fill this gap.

Objectives: Radiation Risk In Mammography Screening (RRIMS) builds on the prototype, formerly known as Breast-iRRISC, to develop a model that aims to establish a dose and risk profile for females by calculating their lifetime mean glandular dose (MGD) for each age of screening between 40 and 75 years, using only the information from her first screening visit. This is then used to allocate her to a dose category and estimate the lifetime risk of radiation-induced breast cancer incidence and mortality for a population of females in that category.

Methods: This model training was developed using a large dataset of Hologic images containing a total of 20,232 images from 5,076 visits from 4,154 females. The female's breast characteristics and exposure parameters were extracted from the images to calculate the female's MGD throughout a lifetime of screening from just her first screening visit, using modelling of various parameters and their change through time.

Results: This development has ultimately provided a model that uses the female's first screening visit to calculate the received MGD for all ages of potential screening. This has enabled the allocation of females to either a low-, medium-, or high-dose category, ultimately followed by the lifetime effective risk (LER) estimation for any screening attendance pattern. A female in the low-dose category undergoing biennial screening from 50 to 74 years would expect a risk of radiation-induced breast cancer incidence and mortality of 8.64 and 2.61 cases per 100,000 females, respectively. Similarly, a female in the medium- or high-dose category undergoing the same regimen would expect an incidence and mortality risk of 11.76 and 3.55, and 15.08 and 4.55 cases per 100,000 females, respectively.

Conclusions: This novel approach of establishing a female's dose profile and lifetime risk from a single visit will further assist females in their informed consent on breast screening attendance and help inform policy-makers when exploring the benefits and drawbacks of various screening patterns and frequencies.

Advances in knowledge: RRIMS is a novel tool that enables the assessment of a female's lifetime dose and risk profile using only the information from her first screening visit.

Quantitative imaging biomarkers (QIBs) are increasingly used in clinical studies. Because many QIBs are derived through multiple steps in image data acquisition and data analysis, QIB measurements can produce large variabilities, posing a significant challenge in translating QIBs into clinical trials, and ultimately, clinical practice. Both repeatability and reproducibility constitute the reliability of a QIB measurement. In this article, we review the statistical aspects of repeatability and reproducibility of QIB measurements by introducing methods and metrics for assessments of QIB repeatability and reproducibility and illustrating the impact of QIB measurement error on sample size and statistical power calculations, as well as predictive performance with a QIB as a predictive biomarker.